In Artificial Intelligence, what are semantic analyses used for?
In Natural Language Processing (NLP), you are dealing with knowledge/intents/... expressed in linguistic structures. For example, if you have a text understanding system, you would read the text, usually sentence by sentence, analyse the syntactic structure, and then the meaning (composed of the word meaning and the structural meaning, plus the pragmatic meaning (based on the situation/context)); in other words, looking at the semantic content of a sentence helps you understand what it is about. An AI system can then process the content towards the goal of understanding the text.

In natural language generation, a semantic representation is turned into text. Here the process in reversed: the meaning of the sentence is known, but the appropriate words and sentence structures have to be chosen by the generator. 

These are two examples where semantic analysis is used in NLP; there are plenty of others, as meaning is central to the processing of natural language.